Multicenter, open label, uncontrolled Phase I pharmacokinetic trial to determine the Maximum Tolerated Dose (MTD) of ST1968 given intravenously (I.V.) once every week for 2 consecutive weeks every 3 weeks and the MTD of ST1968 given I.V. once every 3 weeks. A starting dose of 1.5mg/m2 given as a flat dose of 2.5mg is defined, given once on Day 1, Day 8 every 21 Days (D1, D8 Q21D schedule), over 2 h. Starting dose for the Day 1 every 21 Days (D1 Q21D schedule) has to be determined from the MTD of D1, D8 Q21D schedule.